Andy Serkis’ work in Rise of the Planet of the Apes locks his position amongst legendary ‘monster’ actors such as Lon Chaney, Sr, Lon Chaney, Jr. and Boris Karloff. That might not seem to be the greatest compliment at first; that roster of actors shouldn’t be marginalized so. I think all would bristle at being considered as performers we take seriously only when they work behind makeup and prosthetics or their digital equivalents.

The fact, however, is that Andy Serkis’ best work has been done in conjunction with groundbreaking washes of pixels. Beginning with his portrayal of Gollum in The Lord of the Rings, continuing on through Peter Jackson’s King Kong and now culminating with Caesar, the ape at the center of Rise of the Planet of the Apes, the partnership between the actor and effects house WETA has done far more than most to advance the idea of what the nature of screen acting really is.

Serkis and WETA lend Caesar a moving depth of personality that goes beyond the bounds we’re accustomed to seeing in non-human characters. And, as many of his interactions with the other simian characters are necessarily devoid of dialogue, the film displays a spirit that cuts closer to pure cinema than I expect from the seventh film in the 40-year old franchise.

This prequel to the 1968 Planet of the Apes is, on some levels, an unsatisfying film. Human characters, for example, receive only perfunctory characterization. Beyond that, the story’s thematic development is undercut by a tendency to indulge those characters rather than really dig into the questions that arise when humans accidentally create a race of super-intelligent apes.

But when those apes hit the screen: wow. The digital animals, often performed by humans in motion-capture rigs, then animated by WETA, bring the movie to persuasive life. When director Rupert Wyatt turns his attention to the increasingly intelligent and aware Caesar and the apes he eventually organizes, it’s like he’s making a different movie from the one featuring scenes inhabited by James Franco, Frieda Pinto, Brian Cox and Tom Felton.

Caesar is the son of another chimpanzee, Bright Eyes, one of several animals given an experimental treatment by researcher Will Rodman (Franco). Will seeks a neurological regenerative to cure Alzheimer’s patients, spurred by the illness of his own father (Lithgow). Bright Eyes’ wave of treatment fails, but the unexpected result is Caesar, who displays preternatural intelligence. Secreted from the lab by Will, the chimp grows up in the Rodman household before one difficult ape/human interaction forces Will to give Caesar up to a simian sanctuary overseen by the blinkered John Landon (Cox) and his son Dodge (Felton).

Rise does address questions of human and animal nature and responsibility: what right do we have to create and alter life? How broad is the difference between our species and others? But those questions can only dig so deep when half the film is populated with minor character stubs.

Often in a film of this sort it would be the creatures who are relegated to flashy window-dressing. In this case, it is the humans. Frieda Pinto, for example, plays a character who serves only to interject influence into one or two scenes. And David Hewlett, as the Rodman’s next-door neighbor, is a shallow, angry caricature. In a scene where the elder Rodman’s Alzheimer’s takes a bad turn, Hewlett is called upon to act out the sort of exaggerated, ‘only in a movie’ action that provokes nothing but my disbelief.

Tom Felton is handed a similarly one-note character: an animal hater who works at an animal sanctuary. I can only suppose he is meant to be a distilled and easily dispatched representation of the idea of human superiority over animals. We know that this sneering asshat will get his comeuppance, and that promise is supposed to be enough to get us to sit through his awful actions. The setup and payoff didn’t balance out for me; I just wanted Caesar to chew up the kid so we could move on.

All is quickly forgiven thanks to the depth of feeling we see in Caesar’s eyes, and the pure energy and expression we see in his movements. He and the other sanctuary apes, whose interactions play out with palpable feeling, transform Rise of the Planet of the Apes into character-based sci-fi, rather than simple action spectacle. I’m not a primatologist, so I won’t argue the level of realism as these apes interact. But I will say that I was convinced throughout.

Rupert Wyatt directs with a sense of calm, and seems predominantly concerned with our understanding of unfolding events. (What a shame that such a thing is worth remarking upon, but compared to most of this summer’s big films, it is noteworthy.) When he adds frantic energy to a scene he’s using that energy for purposes of story, rather than in a desperate bid to keep our attention.

In scenes featuring the apes, the direction is often wonderful. We see Caesar grow up — and start to grow out of his human-influenced behavior — in a time-lapse sequence set in amid giant redwoods. Casar moves through the trees at first with youthful exuberance, then with powerful assurance and intent. It’s a simple trick, but used well.

Action scenes are clear and well-choreographed. Each demonstrates a real understanding of physical space, and how to establish characters in physical relation to one another. Wyatt isn’t shy about cutting in close to create a sense of momentum, but more often than not he takes a cue from Peter Jackson’s presentation of battles in The Lord of the Rings to back the camera away from the action and let us understand how the space really works. The result is a collection of setpieces that are tense and exciting.

More fully realized human characters would allow Rise of the Planet of the Apes to feel truly developed. Yet as Caesar develops his own sense of the world, and pushes other apes to evolve, he proves to be forceful enough to drive the film all on his own. I’d like to say that the work done by Andy Serkis is brilliant — and it certainly is — but it is really the combined efforts of Serkis, Rupert Wyatt and WETA that makes the best parts of Rise look like an evolution in creating non-human characters for film.